.\"	$OpenBSD: vscsi.4,v 1.13 2014/06/28 06:42:42 matthew Exp $
.\"
.\" Copyright (c) 2008 David Gwynne <dlg@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: June 28 2014 $
.Dt VSCSI 4
.Os
.Sh NAME
.Nm vscsi
.Nd virtual SCSI controller
.Sh SYNOPSIS
.Cd "vscsi0 at root"
.Pp
.In sys/types.h
.In sys/ioctl.h
.In scsi/scsi_all.h
.In dev/vscsivar.h
.Sh DESCRIPTION
The
.Nm
device takes commands from the kernel SCSI midlayer and makes them available
to userland for handling.
Using this interface it is possible to implement virtual SCSI devices that are
usable by the kernel.
.Pp
The following
.Xr ioctl 2
commands are provided to allow userland to dequeue SCSI commands and reply to
them:
.Pp
.Bl -tag -width Ds -compact
.It VSCSI_I2T Fa "struct vscsi_ioc_i2t *"
Dequeue a SCSI command.
If no SCSI commands are available to dequeue,
.Xr ioctl 2
will fail and set
.Va errno
to
.Dv EAGAIN .
.Pp
When one or more SCSI commands are available to dequeue,
.Xr select 2
will indicate the descriptor as ready to read.
.Bd -literal -offset indent
struct vscsi_ioc_i2t {
	int			tag;

	u_int			target;
	u_int			lun;

	struct scsi_generic	cmd;
	size_t			cmdlen;

	size_t			datalen;
	int			direction;
#define VSCSI_DIR_NONE		0
#define VSCSI_DIR_READ		1
#define VSCSI_DIR_WRITE		2
};
.Ed
.Pp
.It VSCSI_DATA_READ Fa "struct vscsi_ioc_data *"
.It VSCSI_DATA_WRITE Fa "struct vscsi_ioc_data *"
Read or write data in response to a SCSI command identified by tag.
.Bd -literal -offset indent
struct vscsi_ioc_data {
	int			tag;

	void *			data;
	size_t			datalen;
};
.Ed
.Pp
.It VSCSI_T2I Fa "struct vscsi_ioc_t2i *"
Signal completion of a SCSI command identified by tag.
.Bd -literal -offset indent
struct vscsi_ioc_t2i {
	int			tag;

	int			status;
#define VSCSI_STAT_DONE		0
#define VSCSI_STAT_SENSE	1
#define VSCSI_STAT_RESET	2
#define VSCSI_STAT_ERR		3
	struct scsi_sense_data	sense;
};
.Ed
.Pp
.It VSCSI_REQPROBE Fa "struct vscsi_ioc_devevent *"
.It VSCSI_REQDETACH Fa "struct vscsi_ioc_devevent *"
Request a probe or a detach of the device at the addresses specified by the
target and lun fields.
.Bd -literal -offset indent
struct vscsi_ioc_devevent {
	u_int			target;
	u_int			lun;
};
.Ed
.El
.Sh FILES
.Bl -tag -width /dev/vscsi0
.It /dev/vscsi0
.El
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr intro 4 ,
.Xr scsi 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Ox 4.5 .
.Sh AUTHORS
.An David Gwynne Aq Mt dlg@openbsd.org .
